1. Technical Field
The present invention relates to a lamp, a light-emitting device, and a projector.
2. Related Art
A light source device that has been known in related art includes a discharge starting support member made of a metal wire and formed on a discharge lamp that emits light in an electromagnetic field of microwave. In the light source device, an intensity of the electromagnetic field inside of the discharge lamp is increased by focusing the electromagnetic field generated an end of the metal wire. (e.g. JP-A-57-55057 (page 2, FIG. 2))
A light source device disclosed in JP-A-57-55057 makes use of a focus of the electromagnetic field generated at an end of the metal wire. However, the focus of the electromagnetic field generated at the end of the metal wire is limited. Therefore, the light source device disclosed in JP-A-57-55057 has difficulties in further increasing the focus of the electromagnetic field and improving luminance of the discharge lamp.
Consequently, it is conceivable to provide a lamp and a light-emitting device including a coil. In such a lamp and a light-emitting device including a coil, an electric field component of microwave is collected by the coil. Therefore, the electric field component collected is easily focused on a light emitter of the lamp. The coil is easy to make changes in a material, a sectional area, and setting such as a coiling number, thereby facilitating a change of density of the electric field component to be focused. Therefore, the lamp and the light-emitting device including a coil become easy to increase an intensity of an electric field at a light emitter and improve luminance.
Here, the further from the coil, the lower density of the electric field component collected by the coil becomes. Therefore, in order to effectively focus the electric field component collected by the coil on the light emitter of the lamp while the density of the component is high, the coil is preferably placed closer to the light emitter of the lamp. On the other hand, the light emitter of the lamp generates heat while emitting light. Therefore, in accordance with the lamp turned on and off, the coil iteratively receives heat. It is thus conceivable that deterioration of the coil is accelerated. That is, the lamp and the light emitting device including a coil have difficulty in improving their durability.